Now that all the DocBook documentation is gone, we can switch to the
new NixOS documentation generator. No meaningful change in HTML output,
except that I removed the rather pointless preface and changed the
title accordingly. Manual page output is greatly improved; it was
kind of broken before. The `sed` hack is pretty gross but I have
confirmed that nixpkgs will be happy to accept a PR to make things
a little more customizable.
This also drops the `manual` alias (deprecated in nixpkgs in 2018
and imported into nix-darwin), and `manualEpub` (because the NixOS
documentation generator doesn't support it and also nobody wants this
as an ebook).
The only change to `options.json` are that the `declarations` fields
now contain correct GitHub URLs.
The changes to the HTML manual are all either strict improvements:
* "Declared by:" links point to the correct URLs.
* `lib.mdDoc` documentation is included.
or else trivial:
* Additional whitespace in the HTML source.
* Some interchange of `<pre class="programlisting">` and
`<code class="literal">`.
* Fancy quotes used in some type descriptions.
`optionsDocBook` is exported temporarily as it is used by
`nix-doc-munge` for the Markdown conversion process.
This drops support for building the manual on 22.11, which lacks a
complete implementation of this processor, and provides stubbed-out
manual packages with an explanation on that version.